Routers are a type of power tool used to remove material from a workpiece for decorative or functional purposes. In particular, routers may be useful in performing cabinetwork, cutting grooves in the surface or edges of a material, and applying a decorative border to a material through fluting or beading. In general, there are two types of routers, namely fixed base routers and plunge base routers. Both types of routers include an electric motor having a rotating shaft mounted vertically within a housing. The motor shaft terminates with a chuck, clamp, or collet for interchangeably securing a cutting tool, referred to as a router bit, to the shaft for rotation with the shaft. Fixed base routers and plunge base routers exhibit structural differences that affect the method by which a user operates the routers.
Fixed base routers include a motor unit coupled to a base having a motor mount and a work engaging surface. The motor mount is typically connected to the top portion of the base opposite the work engaging surface. Some fixed base routers have two opposing handles associated with the base while other fixed base routers have a grip portion formed as part of the motor unit. These latter routers are sometimes referred to as palm routers. In fixed base routers with handles, the handles are connected to the motor mount and/or the top surface of the work engaging surface. A router bit, coupled to the motor unit, is configured to extend through an opening in the work engaging surface. The amount the router bit extends from the work engaging surface is adjustable depending on the position of the motor unit relative to the motor mount. In particular, the motor mount may include a plurality of different positions in which the motor unit may be locked. The plurality of positions enables a user to make grooves or cuts of a particular depth, depending on which position is selected. In general, a user operates a fixed base router by precisely guiding the rotating router bit around the edges or surface of a workpiece, thereby causing the bit to cut and remove portions of the workpiece at a fixed and predetermined depth.
Plunge base routers include a carriage, two opposing handles, a base plate, and two plunge posts. The plunge posts extend perpendicularly from the base plate and extend into channels formed in the carriage. The carriage is configured to house an electric motor, wherein the rotating shaft of the electric motor extends downward from the carriage toward the base plate. The opposing handles are connected to opposite sides of the carriage. Biasing members are configured to bias the carriage in an upward direction away from the base plate so that the motor shaft and the router bit, if one is attached, are positioned above the base plate, out of contact with a workpiece. A user may apply downward pressure upon the opposing handles, to slide the carriage down the plunge posts toward the workpiece until the router bit extends below the base plate by a predetermined distance. Thus, the term “plunge” refers to the ability of a plunge base router to direct a router bit into contact with a workpiece from the upper position in which the router maintains the rotating router bit above the workpiece, to the lower position in which the router bit is forced into contact with the workpiece. The router may be secured in the lower position with a locking member, thereby permitting a user to relax the downward pressure upon the opposing handles during the routing process. Upon releasing the locking member and the downward pressure on the handles, the biasing system forces the carriage to slide up the plunge posts to the upper position, thereby removing the router bit from contact with the workpiece.
Some routers, referred to as modular or combination routers, are configured to have a motor unit that may be removably connected to the carriage of a plunge base or the motor mount of a fixed base. A user may select the plunge base or the fixed base depending upon the task to be performed with the router. In particular, a fixed base router may be most useful in making cuts or grooves along the outer edges of a workpiece, while a plunge base router may be most useful in making cuts or grooves in the interior surface of a workpiece.
Regardless of the type of router selected, finish carpentry and woodworking are typically time-intensive endeavors. A carpenter or other user wants the reassurance that precise settings, such as depth of cut, are maintained under all operating conditions of the router. A typical wood cutting router may use a screw thread to convert rotational motion, for example from a rotatable dial, to linear motion to position the motor unit relative to the carriage or the motor mount. Once the user rotates the dial to set the desired router position, the user expects that position to be reliably maintained despite vibration during operation of the router or unintentional contact from the user or the work environment.
In view of the foregoing, it would be advantageous to provide a power tool, such as a router, with an unobtrusive lock mechanism that prevents vibration or unintentional contact from changing a set position of the power tool. An ergonomic lock mechanism that provides efficient release of the lock mechanism to allow position adjustment of the power tool would be further advantageous.